1990 EXR a/c, auto, 200500 km

Recently had a dramatic coolant leak with steam and the heat getting into the red zone; I pulled over immediately when I noticed. I had a jug of coolant with me so refilled after 20 minutes or so and tried to drive home. Almost made it but had to refill one more time from a lake. Anyway got it towed (CAA!) and everything fixed: new hose, fresh coolant, and new temperature sensor which I had been meaning to put in for a while (found elsewhere on the forum that this was a fix for the cooling fan coming on every time I shut down — even with a cold engine). Problem now is overheating happens whenever I'm not at a good speed, around 70kmh/40mph. For instance 20 min of city driving got me 3/5 up the heat scale and 25 min of rural driving ending with a slow stretch got the needle up to 3/4. Would this maybe be the water pump? Air in the system (the mechanic is very experienced)? Also A/C light no longer comes on when I try to activate it. Not sure if this is new since the red zoning at the initial hose leak or new since the work in the shop has been done. The A/C has not really been functional for a couple of years due to a freon leak but the light has always come on when the button is pushed. Thanks for any help.

 

It could be water pump or possibly head gasket.

Before assuming anything, unplug the electrical connector that is plugged into the thermostat housing. Jump the connector with a piece of wire. Turn on the car. Do both fans turn on?

 

Are you losing any coolant now?

You mention you got a new temperature sensor. Did you mean temperature switch? Do you know if the fans are coming on? There's probably a relay in the circuit and the circuit will be fused so you need to make sure both are good.

Is the radiator blocked?

When was the last time the thermostat was changed?

Do you know that the engine is indeed hot and the problem is not the gauge itself?

If the mechanic were good, he would have bled and burped the system to remove the air.

Don't keep driving this thing until you figure it out or you'll have a head gasket / head warping issue on your hands. Aluminum heads don't like to be run hot. Anything over one half would make me nervous.

 

Burp the coolant system, need to get all the air out of the coolant system, not sure as to where the bleeder valve is but on my 94 it was next to the thermostat housing.

 

I tried PAhonda's suggestion and, yes, both fans turn on.

basket_case:
I'm not losing coolant.

I don't think the rad is blocked would the mechanic notice that. He's very experienced so I doubt he didn't bleed it well.

The thermostat was last changed 3 yrs/50,000km ago

It was definitely a temp. sensor that was replaced.

The engine is definitely hot, not a faulty gauge as far as I can tell.

Thanks!

 

By the way the oil looks fine as does the coolant — no mixing.

I took the rad cap off (rad was new 50000 km ago) and watched as it warmed up. Did burp a couple of times and squeezed the upper hose and more air came out. Took it for a drive but still overheats. Couldn't see whether the coolant was flowing or not due to engine vibration shaking the coolant.

 

When the engine rises towards hot, do both fans on the radiator turn on?

 

I drove around for awhile getting it hot and then parked and shut off with the temperature gauge at around 3/4; the cooling fan came on right away but nothing from the condenser fan. I'm not sure if the cooling fan comes on at all while in motion.

The a/c light doesn't come on when I push the a/c button in the dash which is something new though air conditioning has been useless anyway for the past couple of years due to freon leak (slowly declining cooling ability).

I did watch the radiator with cap off as it warmed up and squeezed quite a bit more air out. Seems bleeding was done poorly if at all — the shop has an intern… losing all that air does seem to have helped though not sure since it is cooler this evening.

 

You're talking about kilometers & EXR model, so you're not in USA... Disclaimer: it's possible some things are set up differently on your car. Canada? I think the Canadian "EXR" is the same as the US "EX".

When it get hot with the engine running, both fans are supposed to run. Normally you have to idle the engine & maybe even put something over the grille to make that happen. The gauge will go up higher than normal, but NOT very close to 100% before the fans switch on.

When you turn off the engine, (if it's hot enough) then only one fan is supposed to run. So that part is OK.

It's pretty unusual for the fans to be needed when the car is in motion. There's already PLENTY of air moving through there just from the motion of the car.

 

Thanks. I tried idling for 20 min and neither fan came on. Drove at 3000rpm for a while and got needle about 2/3 of the way up the gauge, parked but didn't shut the engine down and still no fan. As soon as I shut the engine off the cooling fan came on… thermostat?